TWI591361B - Three axis magnetic field sensor - Google Patents

Description

Triaxial magnetic field sensor

The present invention relates generally to the field of magnetoelectronic devices, and more particularly to CMOS compatible magnetoelectronic field sensors for sensing magnetic fields in three orthogonal directions.

Sensors are widely used in modern systems to measure or detect physical parameters such as position, motion, force, acceleration, temperature, pressure, and the like. While there are many different sensor types for measuring these and other parameters, these sensor types suffer from various limitations. For example, inexpensive low field sensors - such as those used in an electronic compass and other similar magnetic sensing applications - typically consist of an anisotropic magnetoresistive (AMR) based device. In order to achieve the desired sensitivity and reasonable impedance that is well matched to CMOS, the sensing units of such sensors are typically on the order of a few square millimeters in size. For mobile applications, this AMR sensor configuration is expensive in terms of cost, circuit area, and power consumption.

Other types of sensors have been used - such as Hall effect sensors, giant magnetoresistance (GMR) sensors, and magnetic tunnel junction (MTJ) sensors to provide smaller profile sensors, but such Sensors have their own concerns, such as insufficient sensitivity and can be affected by temperature changes. To address these concerns, MTJ sensors and GMR sensors have been employed in a Wheatstone bridge structure to enhance sensitivity and eliminate temperature dependent impedance changes. Many magnetic sensing techniques inherently respond to an orientation of the applied field without responding to orthogonal axes. In fact, two-axis magnetic field sensors have been developed for electronic compass applications to detect the earth's field direction by using a Wheatstone bridge structure for each sensing axis.

For example, a Hall sensor typically responds to an out-of-plane field component perpendicular to the surface of the substrate, while a magnetoresistive sensor responds to an in-plane applied magnetic field. With these response axes, developing a three-axis sensing solution with a small footprint typically involves a multi-wafer module having one or more wafers disposed at orthogonal angles to one another. In the case of a magnetoresistive sensor, a quadrature in-plane component can be achieved with a fine sensor design, but the out-of-plane response is typically obtained by contact with a vertical bond or reflow of a second wafer that has been mounted vertically (garner ). Since the size of the vertically bonded wafer is typically dominated by the pitch of the pads as determined by the handling constraints, this technique results in a large verticality, high die and assembly cost for the processed package, and due to the need to incorporate the "through wafer" Through-chip vias make wafer-level packaging difficult and expensive.

Accordingly, there is a need for an improved design and fabrication process for forming a single wafer magnetic sensor that responds to an applied magnetic field in three dimensions. There is also a need for a three-axis sensor that can be effectively and inexpensively constructed for use in an integrated circuit structure for use in mobile applications. There is also a need for an improved magnetic field sensor that overcomes the problems of the prior art, such as those outlined above, and their manufacture. Further, other desirable features and characteristics of the present invention will become apparent from the Detailed Description and the appended claims.

A ferromagnetic film-based magnetic field sensor includes a first magnetoresistive sensor, the first magnetoresistive sensor comprising: a substrate having a flat surface; and a first sensing element, the first sense The measuring element has a first side transversely parallel to the planar surface of the substrate, the first sensing element having a second side opposite the first side and having a first opposing edge and a second opposing edge; And a first flux guiding member disposed not parallel to the first side of the substrate and having an end portion close to the first edge and the first side of the first sensing element. An optional second flux guide can be disposed non-parallel to the first side of the substrate and having an end adjacent the second edge and the second side of the first sensing element.

In another exemplary embodiment, a ferromagnetic film-based magnetic field sensor includes a first magnetoresistive sensor, a second magnetoresistive sensor, and a third magnetoresistive sensor. The first magnetic tunneling junction sensor includes a first pinning layer and a first sensing element formed on the first pinning layer, and the second magnetic tunneling surface sensor includes a first a second pinning layer and a second sensing element formed on the second pinning layer and orthogonal to one of the first sensing elements, and the third magnetic tunneling surface sensor includes a third pinning And a third sensing element formed on the third pinning layer, the third pinning layer being disposed at about 45 degrees from each of the first pinning layer and the second pinning layer, and The third sensing element has first and second edges and first and second sides. A flux guide is disposed not parallel to a flat surface of the substrate and has an end adjacent the first edge of the third sensing element and the first side.

100‧‧‧Magnetic field sensor

101‧‧‧First Differential Sensor

102 to 105‧‧‧Sensor components

106 to 109‧‧‧ pinned layer

110‧‧‧Second axis/x axis

111‧‧‧Second differential sensor

112 to 115‧‧‧Sensor components

116 to 119‧‧‧ pinned layer

120‧‧‧first axis/y axis

121‧‧‧ Third Differential Sensor

122 to 125‧‧‧Sensor components

126 to 129‧‧ ‧ pinned layer

130‧‧‧third axis/z axis

132 to 139‧‧‧ flux guides

141 to 144‧‧‧bridge arms

Line 145 to 149‧‧

150‧‧‧Metal stability line

152 to 159 ‧ ‧ extensions

160‧‧‧External application field

161 to 168‧‧ ‧ cladding

170‧‧‧ An anisotropic response

171, 172‧‧‧ horizontal segments

173, 174‧‧‧open section

181 to 183‧‧‧ covered wire

191 to 198 ‧ ‧ cladding

1 illustrates an electronic compass structure using a differential sensor formed from three bridge structures having an MTJ sensor in accordance with an exemplary embodiment; FIG. 2 is a Z-axis bridge of FIG. 1 in accordance with an illustrative embodiment. A portion of the cross section of the structure; FIG. 3 is a diagram of a flux line calculated by simulating two of the four magnetic tunneling junction sensors of FIG. 2 by finite elements; FIG. 4 is a diagram in accordance with another illustrative embodiment 1 is a partial cross section of the Z-axis bridge structure of FIG. 1; FIG. 5 is a partial cross-section of the Z-axis bridge structure of FIG. 1 according to another exemplary embodiment; FIG. 6 is a flux shown in FIG. Another shape of the guide; Figure 7 is another shape of the flux guide shown in Figure 5; Figure 8 is another shape of the flux guide shown in Figure 5; and Figure 9 is a A single (without differential wiring) MTJ sensing element is expressed as a percentage of the sensitivity of the Z sensitivity as a function of one of the cladding spacings of the sensor.

Embodiments of the invention will be described below in conjunction with the following figures in which the same numbers Refers to the same component.

The elements depicted in the drawings are not necessarily to scale. For example, the dimensions of some of the elements are exaggerated as compared to other elements for the purpose of facilitating and improving clarity and understanding. Further, where considered appropriate, reference numerals have been repeated among the drawings to the

The following detailed description is merely illustrative and is not intended to limit the invention or the application. Furthermore, there is no intention to be limited by the scope of the present invention or the invention.

By integrating a high-width-ratio vertical strip that contains a high-permeability material (such as nickel-iron (NiFe)) and its ends near the ground, terminating at the opposite edges and opposite sides of a magnetic sensing element (flux guide) Piece), one of the Z-axis fields can be entered into the XY plane. The flux guides are adapted to draw magnetic flux from a field applied to one of the Z directions, and in doing so, bend the field in a substantially horizontal manner near the ends of the flux guides line. The flux guides are arranged through asymmetry, for example, the flux guide segments are disposed above the left edge of the sensing element in the arms of the four arms of the Wheatstone bridge, and the flux guide segments are Positioned above the right edge of the sensing element in the other two arms, the horizontal component can act in the opposite direction of one of the two pairs of arms, resulting in a strong differential signal. One field applied in either the X direction or the Y direction will be equally projected onto all four arms of the bridge and thus subtracted and does not contribute to the final sensor signal. Elective bridges are included elsewhere on the magnetic sensor wafer for determining the x and Y components of the magnetic signal, and in this manner, by means of, for example, one of the magnetic tunneling junction (MTJ) sensing elements The wafer magnetoresistive sensing module accurately determines a field having a component of all three spatial orientations. The Finite Element Method (FEM) simulation demonstrates that in an optimized setup, a pair of aspect ratio flux guides (eg, 25 nm wide by 500 nm high and extending a few microns in the third direction) will provide approximately on a different component. A signal from 80% of the signal measured in the in-plane (x-axis) field of the same intensity. Additional signals can be obtained by bringing the flux guide closer to the proximity sensor, increasing the flux guide height, and the geometry of the additional shaped guides. Got it. One example is the addition of a horizontal segment that is parallel to the sensing element and that extends over the edge of the sensing element. A further example is the formation of a U-shaped object placed with an internal horizontal segment aligned with the outer edge of the sensing element and terminating the vertical segments at a fixed angle to be partially in the plane of the sensing element The flux guides are extended and a similarly placed box structure is formed. These geometric configurations are used to further enhance the horizontal component of the guided flux and move it to a more central zone of the sensor. A structure having individual 25 nm wide and utilizing vertical strips as flux guides allows for overlay error and is at a rate of 2.5% between one single flux guiding layer and the sensing layer at one of 85 nm misalignment (3 sigma) Produces an apparent x-field to z-field transition (Wheatstone bridge for a differential connection).

The flux guiding layer can be formed by a layer typically used in a magnetic random access memory (MRAM) process flow, during which a bit line and a digit line of a high magnetic permeability magnetic material are coated (such as in a typical Magnetic memory devices) - referred to herein as a flux guide, are used to increase the field factor present to reduce the current required to switch memory storage elements. In a sensor application, the same process flow can be used in conjunction with an optional additional step of removing the bottom of the digit line by sputtering to remove any cladding present at the bottom of the trench. The process flow can be modified to optimize the height and width of the cladding for flux guidance to replace the 500 nm and 25 nm used in the exemplary process described above, respectively.

A method and apparatus for providing multi-axis pinning for a bulk wafer that can be used to form one of a plurality of integrated circuit layers having different reference layers, the different reference layers having three different pinnings, are described in more detail later The orientation and both of the pinning directions are set to be substantially orthogonal via a single pinning material deposition and bulk wafer setting process. As a preliminary step, one or more layers of ferromagnetic and antiferromagnetic materials are etched into a shaped reference layer having a two-dimensional shape having a high aspect ratio, wherein the shape provides a desired pair of reference layers The magnetization direction provides a difference. Depending on the material and the technique used, the final magnetization direction can be oriented along the short or long axis of the forming layer. For example, if the pinning layer is formed by a slightly unbalanced synthetic antiferromagnetic (SAF) patterned to a micro-scale size, the magnetization will follow the short axis. guide. Those skilled in the art will appreciate that the SAF embodiment provides several advantages over the use of a pinned SAF reference layer in a magnetoelectronic device. In other embodiments, the final magnetization can be directed along the long axis by controlling the thickness of the pinned and fixed layers and the extent of the in-plane space of the structure of the patterned pattern. Using shape anisotropy, different magnetization directions can be induced in the reference layers by the presence of heating in one of the orientation fields aligned between the desired magnetization directions of the reference layer. In selected embodiments, the reference layer is heated sufficiently to reduce the material composition of the anisotropy and to allow the shape and external field to dominate the magnetization direction. In this way, when the orientation field is removed, the shape anisotropy directs the magnetization in the desired direction. Upon removal of the orientation field, the magnetization of the reference layers is released to follow the shape of the reference layers to induce a magnetization aligned along the desired axis of the shaped reference layer. An optional compensation field can be applied to help induce orthogonality, and then the reference layers are heated to a phase transition temperature above the antiferromagnetic pinning layer. For example, if two reference layers are formed to have longer dimensions that are perpendicular to each other, the magnetization induced for the two reference layers will be nearly perpendicular to each other.

A number of illustrative embodiments of the present invention will now be described in detail with reference to the drawings. Although various details are set forth in the following description, it is understood that the invention may be practiced without the specific details of the invention described herein. The device designer's specific goals, such as compatibility with process technology or design-related constraints. While this development effort can be confusing and time consuming, it is a matter of routine for those of ordinary skill having the benefit of this disclosure. In addition, the selected aspects are described with reference to the simplified cross-sectional illustrations in the <RTIgt; </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; It is also noted that throughout this detailed description, this document does not describe in detail the design and operation of magnetic sensors, magnetoresistive random access memory (MRAM) design, MRAM operation, semiconductor device fabrication, and other integrated circuit devices. Aspect. While certain materials will be formed and removed to make integrated circuit sensors as part of an existing MRAM fabrication process, the specific procedures for forming or removing such materials are not detailed below, as is known to Such details and non-required consideration of such details to teach familiarity with the technology How to make or use the invention. In addition, the circuit/component layouts and configurations shown in the various figures contained herein are intended to represent illustrative embodiments of the invention. It should be noted that there may be many alternatives or additional circuit/component layouts in a practical embodiment.

FIG. 1 shows a magnetic field sensor 100 formed by a first differential sensor 101, a second differential sensor 111, and a third differential sensor 121. The differential sensors are respectively used to detect along the first The direction of the component of the applied field of one axis 120 (e.g., the y-axis direction), a second axis 110 (e.g., the x-axis direction), and a third axis 130 (e.g., the z-axis direction). The z-axis direction is expressed as a point and a cross line as entering or leaving the page on which Figure 1 is located. Illustrative embodiments of the first sensor 101 and the second sensor 111 are described in detail in U.S. Patent Application Serial No. 12/433,679. As described herein, each of the sensors 101, 111, 121 is formed from a sensing element that is unshielded and connected in a bridge configuration. Therefore, the first sensor 101 is formed by connecting a plurality of sensing elements 102 to 105 to a bridge configuration on a corresponding plurality of pinning layers 106 to 109, wherein the pinning layers 106 to 109 are Each is magnetized in the x-axis direction. In a similar manner, the second sensor 111 is via magnetization in a corresponding plurality of pinning layers 116 to 119 (they are each magnetized in a y-axis direction perpendicular to the magnetization directions of the pinning layers 116 to 119) A plurality of sensing elements 112 to 115 are connected in a bridge configuration. In addition, the third sensor 121 in the same plane as the first sensor 101 and the second sensor 111 is via a corresponding plurality of pinning layers 126 to 129 (these are in the same The magnetization directions of the pinning layers 106 to 109 and the magnetization directions of the pinning layers 116 to 119 are magnetized in the xy-axis direction of 45 degrees), and the plurality of sensing elements 122 to 125 are connected to form a bridge configuration. . In the bridge configuration 101, the sensing elements 102, 104 are formed to have a first easy axis axis direction and the sensing elements 103, 105 are formed to have a second easy axis axis direction, Wherein the first easy magnetization axis direction and the second easy magnetization axis direction are orthogonal with respect to each other and oriented to be equally different from the magnetization directions of the pinning layers 106 to 109. As for the second bridge configuration 111, the sensing elements 112, 114 have a first easy axis axis direction orthogonal to the second easy axis axis direction of one of the sensing elements 113, 115, such that The first easy magnetization axis direction and the second easy magnetization axis direction are oriented to be equally different from the magnetization directions of the pinning layers 116 to 119. In the third bridge configuration 121, the sensing elements 122, 123, 124 and the sensing elements 125 all have pinning magnetization orthogonal to the pinning layers 126, 127, 128 and the pinning layer 129. An easy axis of the direction of the axis. The third bridge configuration 121 further includes flux guides 132-135 disposed adjacent the right edges of the sensing elements 122-125, respectively, and fluxes disposed adjacent the left edges of the sensing sensing elements 122-125, respectively. Guides 136 to 139. Flux guides 132, 137, 134, and 139 are disposed above the sensing elements 122-125, and flux guides 136, 133, 138, and 135 are disposed below the sensing elements 122-125. The arrangement of such flux guides 132 to 139 is subsequently described in detail in FIG. In the sensors 101, 111, 121, there is no need to shield the sensing elements and no special reference elements are needed. In an exemplary embodiment, this is done by using a shape anisotropy technique to reference each of the active sensing elements (eg, 102, 104) to another active sensing element (eg, 103, 105) to establish an x-sensor. And an easy magnetization axis of the reference sensing element that is to be deflected by 90 degrees from each other with respect to the y sensor, and with reference to a sensing of the Z-sensor in a relative manner in response to an applied field in the Z direction The component is achieved. The Z sensor reference will be described in more detail below. The configuration shown in FIG. 1 does not require the advantages of the third sensor 121 structure described in more detail in FIG. 2, and is merely given by way of example.

The first sensor 101 and the second sensor 111 are arranged in orthogonal alignment, and each of the sensors is accompanied by a sense of being uniformly offset from the pinning direction of the sensor and orthogonal to each other. Measure component orientation, the sensors detect component directions of the field applied along one of the first axis and the second axis. Flux guides 132-139 are disposed in the sensor 121 between the arms 141, 143 and the arms 142, 144 in an asymmetrical manner above and below the opposite edges of the elements 122-125. Since the flux guides 132, 134 are placed over the sensing elements 122, 124, the flux from the Z field can be directed to the xy plane along the right side by the flux guide 132 and the flux guide 134. And causing the magnetization of the sensing element 122 and the sensing element 124 to rotate in a first direction toward a higher impedance. Similarly, due to the flux guide 133 and the flux guide 135 flux guide are located below the sensing elements 123, 125, so that the magnetic flux from the Z field can be guided along the right side of the sensing element by the flux guide In the xy plane, the magnetization of the sensing element 123 and the sensing element 125 is caused to rotate in a second direction toward a lower impedance relative to the first direction. Therefore, the sensor 121 can detect the component direction of the field applied along one of the third axes. Although in the preferred embodiment, the flux guides are in a plane orthogonal to the plane of the field sensor, if the angles produced by the flux guides and the sensor are not exactly equal to 90 degrees These flux guides will still function. In other embodiments, the angle between the flux guide and the field sensor can range from 45 degrees to 135 degrees, with the selected exact angle depending on other factors such as ease of manufacture.

As can be seen from the foregoing, a magnetic field sensor can be formed by differential sensors 101, 111, 121 that are used in respective pinning or reference layers 106-109, 116-119 and pinning or reference layer 126. Unshielded sensing elements 102 to 105, 112 to 115 connected to a bridge configuration, and sensing elements 122 to 125 having guided magnetic flux to detect the presence and direction of an applied magnetic field . With this configuration, the magnetic field sensor provides good sensitivity and also provides a temperature compensation property for the bridge configuration.

The bridge circuits 101, 111, 121 can be fabricated such that their manufacturing process has only minor adjustments to control the magnetic orientation of the various sensor layers and the cross-section of the flux guiding structure is part of either an MRAM or a thin film sensor. Each of the pinning layers 106 to 109, 116 to 119, and the pinning layers 126 to 129 may be formed of one or more lower ferromagnetic layers, and the sensing elements 102 to 105, 112 to 115, and the sensing elements 122 to Each of 125 may be formed from one or more upper ferromagnetic layers. An insulating tunneling dielectric layer (not shown) can be disposed on the sensing elements 102-105, 112-115 and the sensing elements 122-125, and the pinning layers 106-109, 116-119, and nails Between layers 126 to 129. It is desirable for the pinning and sensing electrodes to be magnetic materials whose magnetization directions are alignable. Suitable electrode materials commonly used in magnetoresistive random access memory (MRAM) devices and electrodes of other magnetic tunnel junction (MTJ) sensor devices and structures of such materials Configuration is well known in the art. For example, the pinning layers 106-109, 116-119, and the pinning layers 126-129 can be one layer of a combined thickness ranging from 10 Å to 1000 Å and in the selected embodiment from 250 Å to 350 Å or Multi-layer ferromagnetic material and antiferromagnetic material are formed. In an exemplary implementation, each of the pinning layers 106-109, 116-119 and the pinning layers 126-129 is formed from a single ferromagnetic layer and a lower antiferromagnetic pinning layer. In another exemplary implementation, each of the pinned layers 106-109, 116-119 and the pinned layers 126-129 comprise a synthetic antiferromagnetic stack component of 20 Å to 80 Å thick (eg, a stacked CF (cobalt iron) ), ruthenium (Ru) and CFB), and an antiferromagnetic pinning layer of about 200 Å thick. The lower antiferromagnetic pinning material may be a reconfigurable material such as IrMn, although other materials that cannot be easily reset at a suitable temperature, such as PtMn, may be used. When formed, the pinning layers 106 to 109, 116 to 119 and the pinning layers 126 to 129 are used as a fixing or pinning if the direction of magnetization is pinned in one direction which does not change during normal operation. Magnetic layer. As disclosed herein, the thermal qualities of the materials used to pin the pinned layers 106-109, 116-119 and the pinned layers 126-129 can change the manufacturing sequence used to form such layers.

One of the sensing elements 102 to 105, 112 to 115, 122 to 125 and one of the pinning layers 106 to 109, 116 to 119, 126 to 129 form a magnetic tunneling Junction (MTJ) sensor. For example, in the case of the bridge circuit 121, the sensing element 122 and the pinning layer 126 form an MTJ sensor 141. Similarly, the sensing component 123 and the pinning layer 127 form an MTJ sensor 142, the sensing component 124, and the pinning layer 128 form an MTJ sensor 143, and the sensing component 125 and the pinning layer 129 form an MTJ sense. Detector 144.

The pinned layers 106 to 109, 116 to 119 and the pinning layers 126 to 129 may be aligned by a single axis having one of the magnetization directions (indicated by arrows) aligned along the long axis of the reference layer(s). The ferromagnetic layer is formed. However, in other embodiments, the pinning may be performed using a synthetic antiferromagnetic (SAF) for aligning the magnetization of the pinned reference layers along the minor axis of the reference layer of the (equal) pattern. Reference layer. It will be appreciated that the anti-ferromagnetic pinning layer can be combined to implement the SAF layer, but with the appropriate geometric configuration and material to provide a sufficiently strong magnetization. Under the SAF structure, the underlying antiferromagnetic pinning layer can be eliminated, thereby providing a simpler manufacturing process with cost savings.

Sensing elements 102-105, 112-115, 122-125 may be formed from one or more layers of ferromagnetic material having a thickness ranging from 10 Å to 5000 Å and in a selected embodiment from 10 Å to 60 Å. The upper ferromagnetic material may be a soft magnetic material such as NiFe, CoFe, Fe, CFB, and the like soft magnetic material. In each MTJ sensor, the sensing elements 102 to 105, 112 to 115, 122 to 125 function as a sensing layer or a free magnetic layer because the direction of magnetization thereof may be due to an externally applied field such as the magnetic field of the earth. Exist and deviate. Once finally formed, the sensing elements 102-105, 112-115, 122-125 may be formed from a single ferromagnetic layer having a magnetization direction (indicated by an arrow) aligned along a long axis containing the shape of the pattern.

The pinned layers 106-109, 116-119, 126-129, and the sensing elements 102-105, 112-115, 122-125 can be formed to have different magnetic properties. For example, the pinning layers 106 to 109, 116 to 119, 126 to 129 may be formed by an antiferromagnetic film exchange layer coupled to one of the ferromagnetic films to form a high coercive force and an offset hysteresis. The layers of the curve are such that the magnetization directions of the layers will be pinned in one direction and thus substantially unaffected by an externally applied magnetic field. In contrast, the sensing elements 102 to 105, 112 to 115, 122 to 125 may be formed of a soft magnetic material to provide different magnetization directions having a relatively low anisotropy and coercive force, such that Externally applying a magnetic field changes the magnetization direction of the sensing electrode. In selected embodiments, although different ratios can be used by adjusting the composition of the electrodes using well-known techniques to adjust the respective magnetic properties, the strength of the pinning field is approximately greater than the anisotropy field of the sensing electrodes. The magnitude of the magnitude.

The pinning layers 106 to 109, 116 to 119, 126 to 129 in the MTJ sensor are formed to have a shape-determined shape in the plane of the pinning layers 106 to 109, 116 to 119, 126 to 129 The direction of magnetization (identified by the vector arrow labeled "pinning direction" for each sensor bridge in Figure 1). As described herein, the magnetization directions of the pinning layers 106 to 109, 116 to 119, 126 to 129 can be obtained using the shape anisotropy of the pinning electrodes, in which case, A single pinned layer, the shape of the pinned layers 106 to 109, 116 to 119, 126 to 129 in the pinning direction may each become longer in the pinning direction. Alternatively, in the case of a pinned SAF structure, the reference and pinning layers can be made shorter in the pinning direction. In particular, the magnetization directions of the pinned layers 106 to 109, 116 to 119, 126 to 129 may be oriented in a direction that is not orthogonal to the formed pinned layers 106 to 109, 116 to 119, 126 to 129. The shaped pinning layers 106 to 109, 116 to 119, 126 to 129 are first heated under a certain magnetic field of the longest oriented axis such that the applied orientation field is at the pinning layers 106 to 109, 116 to 119, 126. A field component is included in the pinning direction desired to 129. The magnetization directions of the pinned layers are at least temporarily aligned in a predetermined direction. However, by appropriately heating the pinned layers during this process and removing the oriented field without reducing heat, the magnetization of the pinned layer along the shaped pinned layers 106 to 109, 116 to 119, 126 to 129 The desired shaft is released. Once the magnetization is released, the pinned layers can be annealed and/or cooled such that the magnetic field directions of the pinned electrode layers are set in a desired direction of the shaped pinning layers 106-109, 116-119, 126-129. .

The exemplary embodiments described herein can be fabricated using the following known lithography processes. The fabrication of integrated circuits, microelectronic devices, microelectromechanical devices, microfluidic devices, and photonic devices involves the creation of several layers of materials that interact in some manner. One or more of such layers may be patterned such that a plurality of regions of the layer have different electrical or other characteristics that may be interconnected within the layer or interconnected with other layers to establish electrical components and circuitry. Such zones can be established by selectively introducing or removing a variety of materials. The pattern defining such zones is usually established by a lithography process. For example, a layer of photoresist is applied to a layer overlying a wafer substrate. A reticle (containing a clean and transparent region) is used to selectively expose the photoresist material by a form of radiation, such as ultraviolet light, electrons or x-rays. The photoresist material exposed to the radiation or not exposed to the radiation is removed by applying a developer. An etchant is then applied to the layer not protected by the remaining resist, and when the resist is removed, the layer covering the substrate is patterned. Alternatively, an additional process can be used, such as using a photoresist as a template. Build a structure.

Referring to FIG. 2 and according to an exemplary embodiment of the present invention, the structures of the MTJ devices 141 to 144 of the third bridge circuit 121 include all of the pinning layers 126 to 129 and the sensing elements 122 formed in the dielectric material 140. 125 and flux guides 132 to 139. The flux guide 136 is disposed adjacent to a line 145 and has an end disposed below one edge of the sensor element 122. Flux guides 133 and flux guides 138 are disposed on opposite sides of a line 146 and have ends disposed respectively below the edges of the sensor elements 123 and below the edges of the sensor elements 124. The flux guide 135 is disposed adjacent to a line 147 and has an end disposed below one edge of the sensor element 125. The flux guide 132 and the flux guide 137 are separated by an upper wire 148 and have ends disposed respectively above the edge of the sensor element 122 and the edge of the sensor element 123, and the flux guide 134 The flux guide 139 is separated by an upper wire 149 and has ends disposed at edges of the sensor element 124 and above the edges of the sensor element 125, respectively. Line 145 to line 149 are preferably copper, but in some embodiments may be a dielectric. A metal stabilizing line 150 is disposed over the MTJ devices 141 through 144 for providing a stable field to the sensing elements. The ends of the flux guides may be as close as possible to the sensor elements with a preferred spacing of less than or equal to 250 nm therebetween. The sensing elements can be placed as close as possible to form the densest array of densities (preferably less than 2.5 [mu]m).

3 is a diagram of a flux line calculated by simulating the MTJ devices 141, 142 of FIG. 2 with finite elements in the case where one of the magnetic fields in the z direction is applied to the sensing elements 122-123. The FEM patterning shows the resulting flux line 160, which represents a component in the plane of the sensor. The MTJ device 141 is represented by a flux guide 132 and a flux guide 136 on opposite ends of the sensing element 122. The MTJ device 142 is represented by a flux guide 133 and a flux guide 137 on opposite ends of the sensing element 123. Unless otherwise stated, the sensing element 122 extends from the flux guide 132 and the flux guide 136, and the sensing element 123 extends from the flux guide 133 and the flux guide 137. The magnetic field 160 in the Z-axis 130 produces an asymmetrical response (indicated by arrow 170) along the X-axis 120 in the sensing elements 122,123. In this way, it leads to the Z direction towards the bottom of the page. In one of the fields 160 of 130, the magnetization of the sensing element 122 is rotated away from the pinning direction of the pinning layer 126 (and to a higher impedance), while the magnetization of the sensing element 123 is rotated toward the pinning direction of the pinning layer 127. (and turn to lower impedance). With respect to one of the fields in the X direction 120, both elements 122, 123 exhibit induced magnetization (toward higher or lower impedance) in the same direction. Thus, by wiring the MTJ elements 141, 142 into a Wheatstone bridge for differential measurements and subtracting the impedance of the MTJ devices 141, 142, the X field response is eliminated and twice the Z field response is measured.

Referring again to FIG. 2, in the case of an exposure to a large magnetic field (which may cause magnetization disturbances and domain structures in the flux guides 132 to 139), a large current pulse may be introduced along the metal lines 145 to 149. To reset the flux guide domain structure.

In another exemplary embodiment (shown in Figure 4), each of the covered wires 145 through 149 is divided into two separate metal lines with additional non-flux guiding cladding (161 to 168 and 191 to 198). It is placed on the inner edge between the two metal wires. In the case of the sensor 141, the flux guide 161 on the left edge of the left metal line 148 directs the Z field flux to the left side of the sensing element 122 and the rightmost edge of the right metal line 145. The quantity guide 192 directs the Z field flux onto its right side of the sensing element 122. The sensors 142 to 144 function similarly to the cladding edges of the metal lines adjacent to the respective sensing elements functioning as flux guides. Since the lines are separated, a current flowing through the covered wires 145, 146, 182 and the covered wire 183 to the page can be generated and exited by the covered wires 181, 147, 148 and the covered wire 149. The page, in order to establish a Z component along the edge of the covered line, points to a magnetic field in a uniform direction (downward in this example). These current orientations can be used to establish a magnetic field having a strong component in the Z direction, which can be used as a self-test for the function and sensitivity of the Z-axis response after being corrected for one of the geometric configurations.

Another exemplary embodiment (see FIG. 5) includes extensions 152 through 159 that are integrally formed with flux guides 132-139. The extensions 152-159 extend along the same axis as the sensor elements 122-125 and highlight the horizontal component of the flux guide and move the horizontal component more To the center of the appropriate sensing elements 122-125.

Although various exemplary embodiments have been shown for flux guides, including vertical elements 132 through 139 of FIG. 2, and "L" shaped flux guides including extensions 152 through 159 of FIG. 5, other illustrative embodiments It can be used as both an upper flux guide and a lower flux guide, such as a box or "U" shaped flux guide. In the "U"-shaped structure (Fig. 6), a horizontal NiFe segment 171 connects the two vertical segments 161, 162 along the bottom metal line, and in the box-shaped structure (Fig. 8), a horizontal segment 172 is also on the metal line. The square connects two vertical segments. A horizontal segment helps to couple the magnetic structures of the two vertical segments, increasing the magnetic conversion factor by 10% to 20% more than the two isolated vertical flux guides. The two horizontal segments of the box-like structure provide better coupling and increase the field conversion factor by twenty to forty percent more than a simple vertical flux guide. Additionally, the vertical segments of the "U" shaped structure of Figure 6 can be flared outwardly 173, 174 (Fig. 7) such that the region near the edge of the sensing element has a horizontal component. Similar to the L-shaped guide, the open segment directs the magnetic flux such that there is a component directly in the plane of the magnetic sensor to further amplify the field conversion factor. However, care must be taken not to over-large or the magnetic flux will be masked by the sensor.

Figure 9 is a graph showing the Z/X sensitivity ratio versus the cladding/sensor spacing of a 25 nm wide, 500 nm high vertical segment placed above and below the sensing element. As the cladding changes to a distance of 25 nm, the Z/X sensitivity increases to approximately 75%. Additional factors can be obtained by cross-sectional changes such as those highlighted above, or by the aspect ratio in the flux guide. For example, making the guide higher and increasing the aspect ratio will linearly increase the Z/X sensitivity ratio. . Therefore, it is important to have the flux guides as close as possible to the sensing element and to increase the aspect ratio as much as possible without adversely affecting the magnetic microstructure.

Although the exemplary embodiments disclosed herein relate to various sensor structures and methods of fabricating the same, the present invention is not necessarily limited to the illustrative embodiments of the inventive aspects of the present invention. Can be applied to a wide variety of semiconductor processes and / or devices. Therefore, it can be apparent to those skilled in the art who have benefit from the teachings herein. The present invention is to be construed as illustrative and not restrictive. For example, the relative position of the sensing layer and the pinning layer in a sensor structure may be reversed such that the pinning layer is on top and the sensing layer is below. Furthermore, the sensing layer and the pinning layer can be formed from different materials than the disclosed materials. Moreover, the thickness of the layer may deviate from the disclosed thickness values. Accordingly, the description is not intended to be limited to the particulars of the present invention, which is intended to be included within the spirit and scope of the invention as defined by the scope of the appended claims. The modifications and equivalents of the present invention are to be understood by those skilled in the art.

The advantages, particular advantages, and solutions to certain problems with respect to particular embodiments have been described above. However, such advantages, advantages, and solutions, as well as any elements (elements) that will appear or become more significant and which may cause any advantage or advantage, should not be interpreted as a rigorous, , or basic features (features) or components (elements). As used herein, the terms "including ("comprises", "comprising"), "including" ("includes", "including"), "having ("has", "having")" or whatever Other variations are intended to encompass a non-exclusive inclusion, such that a program, element, or device that includes a list of elements (element) can also include not only those elements (element) that are not explicitly listed or included in such a program. , object, or other component of the device.

While at least one exemplary embodiment has been presented in the foregoing detailed description, It is also to be understood that the exemplified embodiments are not intended to limit the scope, application, or configuration of the invention. It is a matter of course that the foregoing detailed description will provide those skilled in the art that the invention can be used to carry out a preferred embodiment of the present invention, but it is to be understood that it can be carried out without departing from the spirit of the invention as set forth in the appended claims. Various changes are made in the function and configuration of the elements described in the exemplary embodiments.

100‧‧‧Magnetic field sensor

101‧‧‧First Differential Sensor

102 to 105‧‧‧Sensor components

106 to 109‧‧‧ pinned layer

110‧‧‧Second axis/x axis

111‧‧‧Second differential sensor

112 to 115‧‧‧Sensor components

116 to 119‧‧‧ pinned layer

120‧‧‧first axis/y axis

121‧‧‧ Third Differential Sensor

122 to 125‧‧‧Sensor components

126 to 129‧‧ ‧ pinned layer

130‧‧‧third axis/z axis

132 to 139‧‧‧ flux guides

141 to 144‧‧‧bridge arms

Claims (10)

A magnetic field sensor includes: a first bridge circuit including a first magnetoresistive sensor coupled to a Wheatstone bridge for sensing one of magnetic fields in a first direction, a second magnetoresistive sensor, a third magnetoresistive sensor, and a fourth magnetoresistive sensor, wherein the first direction is orthogonal to the first magnetoresistive sensor and the second magnetoresistive sensor a first magnetoresistive sensor and a plane of the fourth magnetoresistive sensor; the first magnetoresistive sensor comprises: a first sensing element having a first edge and a second An edge; and a first flux guide comprising a high permeability material, wherein the first flux guide is disposed (i) adjacent to the first sensing element and (ii) to the first sensing Above or below the component; the second magnetoresistive sensor comprises: a second sensing component having a first edge and a second edge; and a second flux guide comprising a high permeability Rate material, wherein the second flux guide is disposed to be (i) adjacent to the second sensing element and (ii) above or below the second sensing element; the third magnetoresistive sensor comprises: First a sensing element having a first edge and a second edge; and a third flux guide comprising a high permeability material, wherein the third flux guide is disposed (i) adjacent to the first a third sensing element and (ii) above or below the third sensing element; and the fourth magnetoresistive sensor comprises: a fourth sensing element having a first edge and a second edge; And a fourth flux guide disposed to (i) adjacent to the fourth sensing element and (ii) Above or below the fourth sensing element. The magnetic field sensor of claim 1, wherein the high permeability material of the at least one of the first flux guide, the second flux guide, and the third flux guide comprises Soft magnetic material. The magnetic field sensor of claim 1, wherein the high magnetic permeability material comprises one or more of the following: nickel, iron, cobalt, and/or one or more of nickel, iron or cobalt. alloy. The magnetic field sensor of claim 1, wherein the first magnetoresistive sensor, the second magnetoresistive sensor, the third magnetoresistive sensor, and the fourth magnetoresistive sensor Each is a magnetic tunneling junction sensor. The magnetic field sensor of claim 1, further comprising: a second bridge circuit comprising a plurality of magnetoresistive sensors electrically coupled together for sensing A magnetic field orthogonal to one of the first directions of the first direction. The magnetic field sensor of claim 1, further comprising: a second bridge circuit comprising a plurality of magnetoresistive sensors electrically coupled together for sensing a magnetic field orthogonal to one of the first directions, wherein the second direction is parallel to the first magnetoresistive sensor, the second magnetoresistive sensor, and the third magnetoresistive sensor And the plane of the fourth magnetoresistive sensor. The magnetic field sensor of claim 1, further comprising: a second bridge circuit comprising a first plurality of magnetoresistive sensors, the first plurality of magnetoresistive sensors being electrically coupled Forming a magnetic field orthogonal to one of the first directions in a second direction; and a third bridge circuit including a second plurality of magnetoresistive sensors, the second plurality of magnetoresistive sensing Electrically coupled together to sense orthogonal to the first direction and the first One of the two directions in one of the third directions. The magnetic field sensor of claim 1, wherein the first bridge circuit includes an input end configured to connect to a power source. The magnetic field sensor of claim 1, wherein the first bridge circuit includes an output end configured to connect to a voltmeter. The magnetic field sensor of claim 1, wherein at least one of the first flux guide, the second flux guide, the third flux guide, and the fourth flux guide Configured as one (bar).